The medical profession often needs to have an objective assessment of the health of the tissue of a patient. The patient may have suffered tissue damage as a result of accidental or deliberate trauma as for example during a surgical operation. The patient may also be suffering some other more persistent irritation as a result, for example, of being confined to bed which can lead to bed sores. It is valuable for a medical practitioner to be able to tell in advance the type of treatment that would benefit the patient.
It is well known, for example, that early detection of tissues displaying pre-cancer or cancer modifications is important for successful medical treatment. We have already disclosed an apparatus and method for carrying out this detection. The invention described in this application represents a significant improvement on the apparatus disclosed in patent application Ser. No. 08/332,830, assigned to the same assignee as the current invention.
Previous probes have had optical components distributed along the length of the probe, for example optical sensors extending via fiber optics to components capable of converting the optical signals into electrical impulses.
Cancerous activity in the human body frequently arises in canals such as the endocervical canal. Visual observation of the health of tissue within these canals is not feasible. For example, in some cases cervical cancer commences in the endocervical canal so it is important that this region be checked for the state of health of the tissue. Because of the narrowness of the canal particularly in younger women, any device which is required to enter must necessarily be of small diameter. A typical maximum permissible diameter is of the order of 3 mm.
It has been established that tissue typing can be determined by making optical and electrical measurements on the tissue. In the narrow confines of the endocervical canal, making optical backscattering measurements on the tissue presents significant difficulties. These measurements need to be confined to small areas in order to maintain the sensitivity of the device to the tissue type. Measurements made over larger areas will necessarily average the properties over that area and will not disclose small regions of abnormality.
To perform optical property measurements over a small area the technology available up to the present has relied on the use of optical fibers to guide the light to and from the area to be examined. This is feasible where the area is relatively accessible. In the case of canals, however, access is limited by the requirement that the device may have to be only of the order of 3 mm diameter, has to look outward at the canal surface and may need to make measurements at several wavelengths.